Importance and evolution of sexual dimorphism in different families of Collembola (Hexapoda)

Abstract

-A bibliographic revision of sexual dimorphism in different families of Collembola was performed in order to determine the most common patterns in each group. We list several examples of the sexual dimorphism in different families of Collembola, which illustrate from some of the smallest differences between males and females to major differences between both sexes in some families. We show different cases of sexual dimorphism in Spinactaletes, Sminthurides, and the remarkable morphology of Guthriella muskegis. It seems that most of the cases of strong sexual dimorphism are related to aquatic habitats or behaviour still not fully understood. Species belonging to primarily aquatic families (fresh water or marine water) have the most evolved morphology, where males have clasping antennae to attach the females in order to avoid loosing them with the movement of the water.Index terms: Guthriella muskegis, morphological variations, secondary sexual characters. Importância e evolução do dimorfismo sexual em diferentes famílias de Collembola (Hexapoda)Resumo -Uma revisão bibliográfica do dimorfismo sexual em diferentes famílias de Collembola foi feita para determinar os padrões morfológicos mais comuns em cada grupo. Foram listados diversos exemplos de dimorfismo sexual em diferentes famílias de Collembola, que ilustram desde as menores diferenças entre machos e fêmeas até as grandes diferenças entre os sexos em algumas famílias. Foi mostrado o dimorfismo sexual em Spinactaletes e Sminthurides, e a morfologia marcante de Guthriella muskegis foi documentada. É provável que a maioria dos exemplos mais evidentes de dimorfismo sexual estejam relacionados ao habitat aquático ou a padrões de comportamento ainda não compreendidos. As espécies que pertencem às famílias aquáticas primárias (água doce ou água marinha) são as que têm morfologia mais evoluída. Os machos têm antenas preênseis, para agarrar as fêmeas e evitar que se desprendam com o movimento da água.Termos para indexação: Guthriella muskegis, variações morfológicas, caracteres sexuais secundários.

Paternal genome elimination promotes altruism in viscous populations

“…More generally, these results may be linked to the extreme sexual dimorphism observed in some of these groups (Gray 1954;Damon 2000;Palacios-Vargas and Castaño-Meneses 2009). Such sexual dimorphism may, in turn, also modulate conditions for social behaviors to evolve (e.g., sex-biased dispersal; Johnstone and Cant 2008;Gardner 2010;Johnstone et al 2012; Supporting Information S6), and thus further modeling is needed to understand how these factors may coevolve with one another.…”

Mating and aggregative behaviors among basal hexapods in the Early Cretaceous

“…In the order Symphypleona there are taxa which exhibit obvious morphological differences between males and females [ 26 ]. One is a peculiar form of the male antennae, and which is particularly conspicuous in the family Sminthurididae [ 26 – 29 ]. Such specializations are present in the newly discovered sminthuridid Pseudosminthurides stoechus from Albian-aged amber from the Peñacerrada I outcrop, which is represented by a well-preserved individual positively identified as a male ( S1 Text ).…”

“…Understandably, sperm transfer is hampered on the water surface. Spermatophores deposited directly on this medium are vulnerable, and direct sperm transfer and morphological modifications to facilitate transfer are common in aquatic species [ 29 ], thereby raising the success of fertilization.…”

“…Accordingly to the specialized morphologies in the Spanish fossil, there must have already been in place a repertoire of stereotyped movements for mating, particularly involving elaborate courtship as evidenced by the clasping antennae, which collectively ensured the appropriate species response and/or positioning for sperm uptake on the water surface. Most of the cases of strong sexual dimorphism are related to aquatic habitats, and where males have clasping antennae to grasp females in order to avoid losing them through movement of currents [ 29 ]. The behavior observed for mating pairs of extant relative S .…”

NEW AQUATIC Sminthurides Börner SPECIES (COLLEMBOLA: SMINTHURIDIDAE) FROM TABASCO, MEXICO

“…Among the Symphypleona, Sminthurididae Börner, is one of the families with most interesting sexual dimorphism (Palacios-Vargas and Castaño-Meneses, 2009), it has 12 genera and close to 150 valid species. Most speciose genera are Sphaeridia Linnaniemi with 70 taxa, Sminthurides Börner with 60 and Denisiella Folsom & Mills with 15 (Bellinger et al 2020), other genera are monospecific or have only 2 or 3 taxa.…”